The present invention relates in general to a semiconductor structure including a crystalline alkaline earth metal nitride-based interface between a silicon substrate and oxides or other nitrides, and more particularly to an interface including an atomic layer of an alkaline earth metal, silicon, and nitrogen.
An ordered and stable silicon (Si) surface is most desirable for subsequent epitaxial growth of single crystal thin films on silicon for numerous device applications, e.g., ferroelectrics or high dielectric constant oxides for non-volatile high density memory and logic devices. It is pivotal to establish an ordered transition layer on the Si surface, especially for subsequent growth of single crystal oxides, e.g., perovskites.
Some reported growth of these oxides, such as BaO and BaTiO3 on Si(100) was based on a BaSi2 (cubic) template by depositing one fourth monolayer of Ba on Si(100) using reactive epitaxy at temperatures greater than 850xc2x0 C. See for example: R. McKee et al., Appl. Phys. Lett. 59(7), pp 782-784 (Aug. 12, 1991); R. McKee et al., Appl. Phys. Lett. 63(20), pp. 2818-2820 (Nov. 15, 1993); R. McKee et al., Mat. Res. Soc. Symp. Proc., Vol. 21, pp. 131-135 (1991); R. A. McKee, F. J. Walker and M. F. Chisholm, xe2x80x9cCrystalline Oxides on Silicon: The First Five Monolayersxe2x80x9d, Phys. Rev. Lett. 81(14), 3014-7 (Oct. 5, 1998). U.S. Pat. No. 5,225,031, issued Jul. 6, 1993, entitled xe2x80x9cProcess for Depositing an Oxide Epitaxially onto a Silicon Substrate and Structures Prepared with the Processxe2x80x9d; and U.S. Pat. No. 5,482,003, issued Jan. 9, 1996, entitled xe2x80x9cProcess for Depositing Epitaxial Alkaline Earth Oxide onto a Substrate and Structures Prepared with the Processxe2x80x9d. However, atomic level simulation of this proposed structure indicates that it likely is not stable at elevated temperatures.
Growth of SrTiO3 on silicon (100) using an SrO buffer layer has been accomplished. T. Tambo et al., Jpn. J. Appl. Phys., Vol. 37 (1998), pp. 4454-4459. However, the SrO buffer layer was thick (100 xc3x85), thereby limiting application for transistor films, and crystallinity was not maintained throughout the growth.
Furthermore, SrTiO3 has been grown on silicon using thick metal oxide buffer layers (60-120 xc3x85) of Sr or Ti. B. K. Moon et al., Jpn. J. Appl. Phys., Vol. 33 (1994), pp. 1472-1477. These thick buffer layers would limit the application for transistors.
Therefore, a thin, stable crystalline interface with silicon is needed.